The bursty nature of highly dynamic loads causes current demands on a power regulator to go, for example, from a few micro Amps (μA) to tens of milli Amps (mA) within a short period of time (e.g., in the order of 3 nanoseconds (ns) for the case of an ultra wideband (UWB) application). Moreover, the power regulator has to recover from the initial burst and be ready for the next burst within a very short period (e.g., 10-20 ns for a pulse position UWB system). Along with this rapidly changing load requirement, there are load regulation specifications that typically restrict the maximum voltage ripple across the load to values below a few tens of milli Volts (mV).
The dynamic requirements typically associated with bursty load operations generally preclude the use of conventional voltage regulation schemes, such as Low Drop Out (LDO) regulators or Switch-Mode Power Supplies (SMPS) which, due to their inherent feedback regulation schemes and relatively low bandwidth, typically cannot react fast enough to the rapid changes of the load profile. As a consequence, one of the regulation aspects is invariably compromised: the ripple voltage, the regulation capabilities, or the regulation capacitance size, which may become undesirably large.
The current solutions to tackle this type of requirements are generally ineffective in solving the problem. For example, the use of an LDO regulator for regulation of such a bursty supply would be difficult for the reason that the loop is not fast enough to regulate the supply within a very short time period (e.g., 12.5 ns). Moreover, the stringent requirements on the maximum droop tolerated generally requires a huge bypass capacitor. Furthermore, the loop bandwidth of the LDO is limited by the stability requirement and an LDO with a few ns response is difficult to realize.